unwelcome speaker noise - heylp me!!

Discussion in 'Amps and Cabs [BG]' started by flamer, Jul 16, 2003.

  1. flamer


    Oct 18, 2002
    swindon, england
    Hi Folks

    I posted about this strange occurrence last week, but i happened again at practice last night, so i need a bit of advice!

    I run a p-bass thru an ashdown abm 500 thru a warwick 210 (400w 8ohm) and a laney 15 (300w 8ohm)
    Occasionally whilst playing my 210 goes crazy and lets out this massive continuous distortion and the speakers move so much it looks like they're gonna pop out. Every time this has happened I have instinctively just hit the amp power switch as I don't want my speakers to die.

    Our guitarist and drummer both think this is due to my bass compactor, which seems to cause feedback when compression is set high. I was sceptical at first, but now i don't know, could this be a factor?

    Another symptom is that the VU meter fly's into the red when this happens.


  2. wulf


    Apr 11, 2002
    Oxford, UK
    Bass compactor? Is that in the signal chain before the Ashdown head?

    If the Ashdown VU meter is going into the red area, it suggests that the input signal is way too powerful as soon as it reaches the amp. Of course, if something IN the amp is playing up, that could (I guess) also screw with the VU meter.

    How often does it happen? You could drop the bass compactor but you wouldn't be sure it was cured until it never happened again....

  3. flamer


    Oct 18, 2002
    swindon, england
    Yeah, it's a compression pedal that i run the precision through into the ashdown.

    It's happened twice in two practices, thing is, if it happens for any length of time, it will kill my speakers!

    The odd think is, this only happens to the 210 speaker, the 15 seems to carry on happily!

    I was wondering if the compression could be sustaining a certain frequency that the 210 can't take?

    Or is that rubbish?
  4. Mcrelly


    Jun 16, 2003
    Minnesota, USA
    I had a compactor and I never ran the compression past 10 o'clock (min is at 7 o'clock) anyway is the erratic cone movement directly related to the notes you are playing or do you actually get feed back? "whistling" or "howling" maybe if your bass knob is set too high with volume and a high compactor setting, maybe? just before I got rid of my compactor I was playing at 9 o'clock max, then I got my G&L SB-1 and the signal was to hot out of the guitar and the minimum setting was not satisfactory on the compactor.

    Try playing without the compactor for one practice and see if it happens.
  5. flamer


    Oct 18, 2002
    swindon, england
    compression was at about 12oclock i think...

    the sound will not stop if i mute my strings.

    turning down volume on my amp/bass obviously stops it, but the minute i turn up even a little way causes the speakers and VU meter to go mad.

    It's not like other feed back i've experienced in the fact that it will not stop until i kill the power.

    wish i'd had the forethought to stomp the pedal off, but i panicked!

    I love my ashdown, but sometimes i wish i bought an amp with in built compression/limiter!
  6. Petebass


    Dec 22, 2002
    QLD Australia
    You know when plug a lead into an amp, then touch the lead with your finger, it makes that rumbly buzz noise. Use something metal instead of your finger and it makes a sound similar to the one you described. We all know this because everyone at some stage has tried to plug in their bass without realising their amp is turned up.

    So my guess is something before the amp is faulty. It sounds like you're getting a loose metal on metal connection somewhere. It could even be a faulty jack on the bass, though the pedal is the more likely culprit. Check your leads as well.

    I don't know why the 15 is immune. You've stumped me on that one.
  7. wulf


    Apr 11, 2002
    Oxford, UK
    Are you sure about turning down the volume on the bass affecting it? That would suggest a problem with the bass itself, which I'd be surprised about.

    Really you need to see if you can get the problem to occur again so that you can work out a solution. When it happens, try working backwards, so:

    * turn master volume to zero (protecting the speakers)

    * turn the pre-amp volume down to zero (does the VU meter come out of the red? Does that happen before you reach zero volume?)

    * assuming you've now got no visible signal hitting the amp, you need to turn the pre-amp volume up enough to get some signal (otherwise you won't know when it's fixed)

    * try turning the stomp box off. If that works, turn it back on and adjust the controls to see if you can stop it

    * etc...

    Bit by bit, you're trying to find the bit of the signal chain that is acting out of control... you may well have to get it repaired / replaced but at least you can focus in rather than having to get the whole setup overhauled.

  8. thumbtrap


    Jun 26, 2003
    It almost sounds like the setup is motorboating at a low enough frequency that the 10's are completely unloaded and the 15 may not be.